Python中requests库使用方法详解

2023-05-16

python中requests库使用方法详解

前言：
- 一、什么是Requests
- 二、安装Requests库
- 三、各种请求方式
- - 1. 基本的GET请求
  - 2. 带参数的GET请求
  - 3. 解析json
  - 4. 获取二进制数据
  - 5. 添加headers
  - 6. 基本POST请求
- 三、响应
- 四、高级操作
- - 1. 文件上传
  - 2. 获取cookie
  - 3. 会话维持、模拟登陆
  - 4. 代理设置
  - 5. 异常处理

前言：

开发环境：Windows10专业版
开发软件：Pycharm Community 2022.3

一、什么是Requests

Requests 是⽤Python语⾔编写，基于urllib，采⽤Apache2 Licensed开源协议的 HTTP 库。它⽐ urllib 更加⽅便，可以节约我们⼤量的⼯作，完全满⾜HTTP测试需求。

二、安装Requests库

在前面的Python基础中我们已经在电脑中配置好了Python环境

如果你还没有安装Python环境可以参考我的这篇文章Python基础——0.Python环境的安装___H2__的博客-CSDN博客

进入命令行win+R执行命令提示符

输入：pip install requests 即可开始安装requests库

项目导入requests：import requests

三、各种请求方式

各种请求方式的使用方法是：

import requests

requests.post('http://httpbin.org/post')
requests.put('http://httpbin.org/put')
requests.delete('http://httpbin.org/delete')
requests.head('http://httpbin.org/get')
requests.options('http://httpbin.org/get')

这五种请求的意义分别是：

GET：请求指定的页面信息，并返回实体主体。
HEAD：只请求页面的首部。
POST：请求服务器接受所指定的文档作为对所标识的URI的新的从属实体。
PUT：从客户端向服务器传送的数据取代指定的文档的内容。
DELETE：请求服务器删除指定的页面。

**get 和 post比较常见 **

GET:请求将提交的数据放置在HTTP请求协议头中；

POST:提交的数据则放在实体数据中

1. 基本的GET请求

import requests
 
response = requests.get('http://httpbin.org/get')
print(response.text)

返回结果：

<!DOCTYPE html>
<!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/bdorz/baidu.min.css><title>ç™¾åº¦ä¸€ä¸‹ï¼Œä½ å°±çŸ¥é“</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=ç™¾åº¦ä¸€ä¸‹ class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>æ–°é—»</a> <a href=http://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>åœ°å›¾</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>è§†é¢‘</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>è´´å§</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&amp;tpl=mn&amp;u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>ç™»å½•</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">ç™»å½•</a>');</script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">æ›´å¤šäº§å“</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>å
³äºŽç™¾åº¦</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>&copy;2017&nbsp;Baidu&nbsp;<a href=http://www.baidu.com/duty/>ä½¿ç”¨ç™¾åº¦å‰å¿
è¯»</a>&nbsp; <a href=http://jianyi.baidu.com/ class=cp-feedback>æ„è§åé¦ˆ</a>&nbsp;äº¬ICPè¯030173å·&nbsp; <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>

2. 带参数的GET请求

将name和age传进去

import requests
response = requests.get("http://httpbin.org/get?name=germey&age=22")
print(response.text)
{
  "args": {
    "age": "22", 
    "name": "germey"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Connection": "close", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.18.4"
  }, 
  "origin": "183.64.61.29", 
  "url": "http://httpbin.org/get?name=germey&age=22"
}

或者使用params的方法：

import requests
 
data = {
 'name': 'germey',
 'age': 22
}
response = requests.get("http://httpbin.org/get", params=data)
print(response.text)

输出结果：

{
  "args": {
    "age": "22", 
    "name": "germey"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.28.2", 
    "X-Amzn-Trace-Id": "Root=1-63dbab1e-10a0b6a747231aa8069318fb"
  }, 
  "origin": "117.44.70.180", 
  "url": "http://httpbin.org/get?name=germey&age=22"
}

3. 解析json

将返回值以json的形式展示：

import requests
import json
 
response = requests.get("http://httpbin.org/get")

print(type(response.text))
print(response.json())
print(json.loads(response.text))
print(type(response.json()))

运行结果：

<class 'str'>

{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Connection': 'close', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '183.64.61.29', 'url': 'http://httpbin.org/get'}

{'args': {}, 'headers': {'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Connection': 'close', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.18.4'}, 'origin': '183.64.61.29', 'url': 'http://httpbin.org/get'}

<class 'dict'>

4. 获取二进制数据

记住返回值.content就ok了

import requests
 
response = requests.get("https://github.com/favicon.ico")
print(type(response.text), type(response.content))
print(response.text)
print(response.content)

返回值是非常长的01二进制字符串所以在此不做演示。

5. 添加headers

在访问次数过多被服务器认定为爬虫攻击时，短时间内可能会将你的IP封禁，这代表你两个小时内将无法使用继续你的爬虫代码调试

，所以我们一般会添加hearder参数。

当传入headers时：

import requests
 
headers = {
 'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36'
}
response = requests.get("https://www.csdn.net/", headers=headers)
print(response.text)

输出结果是csdn首页的html页面源代码

6. 基本POST请求

import requests
 
data = {'name': 'germey', 'age': '22'}
response = requests.post("http://httpbin.org/post", data=data)
print(response.text)

运行结果：

{
  "args": {}, 
  "data": "", 
  "files": {}, 
  "form": {
    "age": "22", 
    "name": "germey"
  }, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Content-Length": "18", 
    "Content-Type": "application/x-www-form-urlencoded", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.28.2", 
    "X-Amzn-Trace-Id": "Root=1-63dbac35-180f5a89233e7d6b4fe75688"
  }, 
  "json": null, 
  "origin": "117.44.70.180", 
  "url": "http://httpbin.org/post"
}

三、响应

import requests

response = requests.get('https://www.jianshu.com/')
print(type(response.status_code), response.status_code)
print(type(response.headers), response.headers)
print(type(response.cookies), response.cookies)
print(type(response.url), response.url)
print(type(response.history), response.history)

运行结果：

<class 'int'> 403
<class 'requests.structures.CaseInsensitiveDict'> {'Server': 'Tengine', 'Date': 'Thu, 02 Feb 2023 12:28:21 GMT', 'Content-Type': 'text/html', 'Transfer-Encoding': 'chunked', 'Connection': 'keep-alive', 'Vary': 'Accept-Encoding', 'Strict-Transport-Security': 'max-age=31536000; includeSubDomains; preload', 'Content-Encoding': 'gzip'}
<class 'requests.cookies.RequestsCookieJar'> <RequestsCookieJar[]>
<class 'str'> https://www.jianshu.com/
<class 'list'> []

状态码判断：常见的网页状态码：

100: ('continue',),
101: ('switching_protocols',),
102: ('processing',),
103: ('checkpoint',),
122: ('uri_too_long', 'request_uri_too_long'),
200: ('ok', 'okay', 'all_ok', 'all_okay', 'all_good', '\\o/', '✓'),
201: ('created',),
202: ('accepted',),
203: ('non_authoritative_info', 'non_authoritative_information'),
204: ('no_content',),
205: ('reset_content', 'reset'),
206: ('partial_content', 'partial'),
207: ('multi_status', 'multiple_status', 'multi_stati', 'multiple_stati'),
208: ('already_reported',),
226: ('im_used',),
 
# Redirection.
300: ('multiple_choices',),
301: ('moved_permanently', 'moved', '\\o-'),
302: ('found',),
303: ('see_other', 'other'),
304: ('not_modified',),
305: ('use_proxy',),
306: ('switch_proxy',),
307: ('temporary_redirect', 'temporary_moved', 'temporary'),
308: ('permanent_redirect',
 'resume_incomplete', 'resume',), # These 2 to be removed in 3.0
 
# Client Error.
400: ('bad_request', 'bad'),
401: ('unauthorized',),
402: ('payment_required', 'payment'),
403: ('forbidden',),
404: ('not_found', '-o-'),
405: ('method_not_allowed', 'not_allowed'),
406: ('not_acceptable',),
407: ('proxy_authentication_required', 'proxy_auth', 'proxy_authentication'),
408: ('request_timeout', 'timeout'),
409: ('conflict',),
410: ('gone',),
411: ('length_required',),
412: ('precondition_failed', 'precondition'),
413: ('request_entity_too_large',),
414: ('request_uri_too_large',),
415: ('unsupported_media_type', 'unsupported_media', 'media_type'),
416: ('requested_range_not_satisfiable', 'requested_range', 'range_not_satisfiable'),
417: ('expectation_failed',),
418: ('im_a_teapot', 'teapot', 'i_am_a_teapot'),
421: ('misdirected_request',),
422: ('unprocessable_entity', 'unprocessable'),
423: ('locked',),
424: ('failed_dependency', 'dependency'),
425: ('unordered_collection', 'unordered'),
426: ('upgrade_required', 'upgrade'),
428: ('precondition_required', 'precondition'),
429: ('too_many_requests', 'too_many'),
431: ('header_fields_too_large', 'fields_too_large'),
444: ('no_response', 'none'),
449: ('retry_with', 'retry'),
450: ('blocked_by_windows_parental_controls', 'parental_controls'),
451: ('unavailable_for_legal_reasons', 'legal_reasons'),
499: ('client_closed_request',),
 
# Server Error.
500: ('internal_server_error', 'server_error', '/o\\', '✗'),
501: ('not_implemented',),
502: ('bad_gateway',),
503: ('service_unavailable', 'unavailable'),
504: ('gateway_timeout',),
505: ('http_version_not_supported', 'http_version'),
506: ('variant_also_negotiates',),
507: ('insufficient_storage',),
509: ('bandwidth_limit_exceeded', 'bandwidth'),
510: ('not_extended',),
511: ('network_authentication_required', 'network_auth', 'network_authentication'),

四、高级操作

1. 文件上传

使用 Requests 模块，上传文件也是如此简单的，文件的类型会自动进行处理：

import requests
 
files = {'file': open('cookie.txt', 'rb')}
response = requests.post("http://httpbin.org/post", files=files)
print(response.text)

通过测试网站做的一个测试

我们先在当前Python文件的目录下建一个名为hello.txt的文本文档，在里面输入helloworld！

保存此文件后运行以上代码，输出结果如下:

{
  "args": {}, 
  "data": "", 
  "files": {
    "file": "helloworld!"
  }, 
  "form": {}, 
  "headers": {
    "Accept": "*/*", 
    "Accept-Encoding": "gzip, deflate", 
    "Content-Length": "156", 
    "Content-Type": "multipart/form-data; boundary=2954083cd56e685e1b45f9840426b548", 
    "Host": "httpbin.org", 
    "User-Agent": "python-requests/2.28.2", 
    "X-Amzn-Trace-Id": "Root=1-63dbad05-039a79aa0adbc2733eab773b"
  }, 
  "json": null, 
  "origin": "117.44.70.180", 
  "url": "http://httpbin.org/post"
}

2. 获取cookie

当需要cookie时，直接调用response.cookie:(response为请求后的返回值)

import requests

response = requests.get("https://www.baidu.com/")
print(response.cookies)

for key, value in response.cookies.items():
    print(key + '=' + value)

输出结果：

<RequestsCookieJar[<Cookie BDORZ=27315 for .baidu.com/>]>
BDORZ=27315

3. 会话维持、模拟登陆

如果某个响应中包含一些Cookie，你可以快速访问它们：

import requests
 
r = requests.get('http://www.google.com.hk/')
print(r.cookies['NID'])
print(tuple(r.cookies))

要想发送你的cookies到服务器，可以使用 cookies 参数：

import requests

headers = {
    "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/"
                  "537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36"
}

# 在Cookie Version 0中规定空格、方括号、圆括号、等于号、逗号、双引号、斜杠、问号、@，冒号，分号等特殊符号都不能作为Cookie的内容。

cookies = {"cookie_name": "cookie_value", }
response = requests.get("https://www.baidu.com", headers=headers, cookies=cookies)
print(response.text)

输出结果是网页的html代码

4. 代理设置

在进行爬虫爬取时，有时候爬虫会被服务器给屏蔽掉，这时采用的方法主要有降低访问时间，通过代理ip访问，如下：

import requests
 
proxies = {
 "http": "http://127.0.0.1:9743",
 "https": "https://127.0.0.1:9743",
}
 
response = requests.get("https://www.taobao.com", proxies=proxies)
print(response.status_code)

ip可以从网上抓取，或者某宝购买

超时设置

访问有些网站时可能会超时，这时设置好timeout就可以解决这个问题

import requests
from requests.exceptions import ReadTimeout

try:
     response = requests.get("http://httpbin.org/get", timeout = 0.5)
     print(response.status_code)
except ReadTimeout:
     print('Timeout')

正常访问，状态码将返回200，超时则会输出Timeout

5. 异常处理

遇到网络问题（如：DNS查询失败、拒绝连接等）时，Requests会抛出一个ConnectionError 异常。

遇到罕见的无效HTTP响应时，Requests则会抛出一个 HTTPError 异常。

若请求超时，则抛出一个 Timeout 异常。

若请求超过了设定的最大重定向次数，则会抛出一个 TooManyRedirects 异常。

所有Requests显式抛出的异常都继承自 requests.exceptions.RequestException 。

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